The present proposal is a plan to continue and even expand the Dallas Lifespan Brain Study (DLBS) for five additional years. The DLBS is possibly the largest and most complete cross-sectional lifespan study that currently exists that integrates structural and functional brain imaging measures, as well as amyloid imaging to understand and predict cognitive function. At the end of the first five year period, the final sample In the study Includes 425 adults from age 20 to 90, with a minimum of 50 subjects in each age decade. Because the cognitive neuroscience of aging is still a very young science, there are very few studies of longitudinal change in neural function. In fact, most large studies of brain and behavior that have a longitudinal component include only structural imaging, and many of these studies were not designed as brain/behavior studies. The Dallas Lifespan Brain Study was designed from its inception to be a longitudinal study of neurocognitive function and the present proposal is focused on adding a four year follow-up testing interval to the study. This will allow us to assess how neural structure and function change after a four-year interval at each decade of the life-span, and whether neural signatures associated with high or low performance at initial testing are predictive of negative trajectory of change in cognition and neural structure and function. At present, subjects admitted to the DLBS are highly screened and selected. The older subjects. In particular, must be optimally aging to meet the screening criteria. We propose to add an additional 180 subjects to the original sample who are typically aging and who have an exclusion factor or are of lower education than the present DLBS sample. The contrast of subjects who are perhaps more representative of the aging population with highly selected subjects will provide one of the first pictures of the neurocognitive health of these two different populations. RELEVANCE (See instructions): This project provides fundamental information about when in the lifespan the onset of cognitive dysfunction and neuropathology occurs. The findings from this project could play a key role in Identifying high-risk individuals relatively early in life for cognitive interventions and Alzheimer's Disease prevention as treatments become available.